Hand Full Of Pills And Vitamins

The immune system’s function is to defend the body against disease-causing microorganisms.  Sometimes the immune system fails, and a virus or bacteria invades and make an individual ill.  Is it possible to intervene in the process and boost the immune system via diet, vitamins, or herbal preparations?   Are positive lifestyle changes effective in boosting the immune system?  For the immune system to function properly, it requires balance and harmony.  The immune system functions better when bolstered by healthy living strategies such as these:

  • Don’t smoke.
  • Eat a diet high in fruits and vegetables.
  • Exercise regularly.
  • Maintain a healthy weight.
  • If you drink alcohol, drink only in moderation.
  • Get adequate sleep.
  • Wash your hands thoroughly to avoid infection.
  • Try to minimize stress.

As we age, our immune system response decreases which makes us more susceptible to infections and various types of cancer. Individuals over the age of 65 can be at higher risk for mortality from respiratory infections, influenza, COVID-19 virus and pneumonia.

Scientists have observed that this increased risk is correlated with a decrease in T-cells, possibly due to the thymus atrophying with age and reproducing fewer T-cells to fight off infection.  T-cells are a type of white blood cell which destroys invaders in the body.  There appears to be a connection between nutrition and immunity in the elderly population.   Older adults generally have a decline in eating and possibly less variety in their diets and therefore may become deficient in some essential vitamins and trace minerals.  Taking a daily multivitamin and mineral supplement may bring other health benefits, beyond having positive effects on the immune system.

Vitamin C is a water-soluble vitamin and an essential nutrient which supports normal growth and development and a healthy immune system.  Vitamin C keeps the skin healthy by boosting collagen and can also promote wound healing.  Food sources of vitamin C include oranges, strawberries, chopped red pepper, and broccoli.  The recommended daily amount for adults is 65 to 90 mg.  The upper limit is 2000 mg daily.  Although too much vitamin C is unlikely to be harmful, a megadose of vitamin C supplements can cause diarrhea, nausea/vomiting, abdominal cramps, and insomnia.  Vitamin C is also known for its antioxidant properties.  It can neutralize unstable compounds in your body called free radicals and help reverse cellular damage caused by these free radicals.

It is important to remember that no supplement will cure or prevent disease.  There are claims on social media that vitamin C can help with COVID-19 (coronavirus).  Physicians and researchers are studying the effects of increased doses of intravenous (IV) vitamin C on the coronavirus.  High dose IV vitamin C has been used in China to help improve lung function in individuals with COVID-19.  Vitamin C’s effectiveness is still being tested, but currently there is no evidence to support the use of oral vitamin C supplements for COVID-19.

Zinc is a micronutrient which is essential for the immune and endocrine systems. It can increase the white blood cell (WBC) count in zinc-deficient patients and benefits the immune response in healthy individuals.  Zinc is also used in healing of wounds.   A deficiency of zinc affects the immune system’s ability to function properly, resulting in an increased risk of infection and disease, including pneumonia.  Zinc deficiency affects around 2 billion individuals worldwide with up to 30 percent of older adults being deficient.

Sources of zinc include beef and seafood and vegetarian sources such as wheat germ, beans, nuts and tofu.  Various scientific studies have shown zinc lozenges to be effective in shortening the course of the common cold.  In the face of a coronavirus pandemic, can zinc shorten the duration of the infection and decrease the symptom load thereby lessening the impact of COVID-19?  According to the current research, it is still too early to determine if zinc supplementation will be effective.  Taking zinc long term is generally safe for healthy adults if the daily dose is under the set upper limit of 40 mg of elemental zinc.  Excessive doses may interfere with copper absorption and could increase the risk of infection.

Vitamin D plays an important role in the function of immune cells, including T-cells and macrophages that protect your body against bacteria and viruses.  Research shows that having healthy levels of vitamin D can help keep your immune system functioning properly.  Vitamin D promotes calcium absorption in the gut and is also needed for bone growth and remodeling.  Vitamin D and calcium help protect older adults from osteoporosis.   Some common sources of Vitamin D include fatty fish such as salmon, tuna, mackerel, eggs, milk and 100 percent juices fortified with vitamin D and ready-to-eat cereals fortified with vitamin D.   Vitamin D is also obtained from sun exposure.  Too much vitamin D can cause toxicity and result in anorexia, weight loss, polyuria, and heart arrhythmias.  Too much vitamin D can also raise blood levels of calcium which can lead to vascular and tissue calcification.  This in turn can damage heart, blood vessels, and kidneys.

A vitamin D deficiency is linked to compromised lung function which may affect the body’s ability to fight respiratory infections.   There have not been any studies investigating the effect of vitamin D supplements or vitamin D deficiency on risk of contracting COVID-19.  The recommended dietary allowance for most 51 to 70-year-old individuals is 600 IU and 800 IU for those greater than 70 years old.  Most experts agree that an optimal vitamin D level is 30 to 60 ng/ml, but this range may vary.  Having healthy vitamin D levels can enhance immune health.

The best line of defense right now against COVID-19 is handwashing, social distancing and wearing a face mask.



  1. Can Supplements Help Combat COVID-19?  Psychology Today, March 20, 2020.
  2. Cara, Anitra C., A New Clinical Trial To Test High-Dose Vitamin C in Patients With COVID-19, Critical Care, Volume 24, Number 133, April 7, 2020.
  3. Ellis, Esther, MS, RDN, LDN, How to Keep Your Immune System Healthy, eatright.org/health/wellness/preventing-illness/how-to-keep-your-immune-system-healthy, March 2020.
  4. Harvard Health Publishing, How to Boost Your Immune System, health.harvard.edu/staying healthy/how-to-boost-your-immune-system, April 6, 2020.
  5. Kubala, Jillian, MS, RD, Can Vitamin D Lower Your Risk of COVID-19? healthline.com/nutrition/vitamin-d-coronavirus, March 26, 2020.
  6. Kubala, Jillian, MS, RD, The 15 Best Supplements to Boost Your Immune System Right Now, healthline.com/nutrition/immune-boosting-supplements, May 8, 2020.
  7. National Institutes of Health Office of Dietary Supplements Vitamin D Fact Sheet for Health Professionals, ods.od.nih.gov/factsheets/Vitamin D-HealthProfessional/, March 24, 2020.
  8. Neff, Todd, Coronavirus:  To Zinc or Not To Zinc? uchealth.org/today/zinc-could-help-diminish-extent-of-covid-19/, March 25, 2020.
  9. Shoemaker, SaVanna, MS, RDN, LD, Can Vitamin C Protect You From COVID-19? healthline.com/nutrition/vitamin-c-coronavirus, April 2, 2020.
  10. Zeratsky, Katharine, RD, LDN, Nutrition and Healthy Eating:  Is It Possible to Take Too Much Vitamin C? mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating.